Call of Duty: Modern Warfare 2 Walkthrough & Strategy Guide

Save first room of hostages and go to deck two. In the storage room where you are warned about an enemy gunship, check the equipment rack for the laptop.

After saving hostages on deck two and placing Plan-B, check the corner room near the stairs leading from second deck to third deck. The laptop is again on a storage rack.

On the third level, there are stairs going up then down towards some enemies near fake (or non-interactive) weapon crates. Around this time, MacTavish or Ghost will say something about using the hallways to get around and ambush enemies. Check under the stairs in the rig's interior for the laptop.